Biogas derived from municipal solid waste to generate electrical power through solid oxide fuel cells

Abstract

Depleting fossil fuels and the pollution resulting from their consumption indicate an urgent need for clean and dependable alternatives such as renewable energies. Biomass is a free and abundant source of renewable energy. Municipal solid waste (MSW) as one of the main categories of biomass has always been an issue for metropolitan cities. It has, however, a high potential for biogas production.

In this study, the technical and economic aspects of generating electrical power through solid oxide fuel cells (SOFCs) powered by injecting biogas derived from Tehran's MSW, as a case study, are investigated. The main objectives of the current study are to identify the power generation capability of the process and find out if it can result in a competitive energy resource. The total amount of obtainable methane through anaerobic digestion of MSW and then the achievable power generation capacity by using the obtained biogas are computed using the electrochemical relations inside the SOFC. The economic calculations are carried out to estimate the final price of the generated electricity, taking into account the major capital and ongoing costs of the required equipment. The effect of variations of MSW composition on the power generation capability and final electricity price is also studied. Moreover, the application of a gas turbine (GT) with the SOFC as a hybrid SOFC–GT system to recover the produced heat by SOFC and its effect on the power generation capability and the final electricity price are investigated.

Results indicate that around 997.3 tons day−1 biomethane can be generated using Tehran's MSW. By using the SOFC, the produced biogas can generate 300 MWAC electrical power with a final cost of $0.178 kWh−1. By using the hybrid SOFC–GT, the electrical power capacity is increased to 525 MWAC, and the final electricity cost drops to $0.11 kWh−1, which indicates its competitiveness with other common energy resources in the near future, especially by considering different governmental subsidy policies that support renewable energy resources. The considerable environmental benefits of the proposed procedure, from both MSW management and CO2 emission reduction points of view, make it a promising sustainable energy resource for the future.